Though he owns a summer home in Bourne, Cape Cod ties haven't yet translated into campaign cash for William Keating.

The first candidate to reach $500,000 in the race for the 10th Congressional District, Keating has so far received the fewest donations from the Cape and Islands among the top four candidates. In fact, the Norfolk County district attorney is getting 77 cents of every $1 dollar donated to his campaign from outside the district, according to federal records.

More than half of those funds were originally part of the war chest Keating had amassed to run for state attorney general. Because federal fundraising law prohibits using money raised in a state campaign in a federal election, Keating returned $370,000 to donors and asked them to write a check to his congressional campaign instead.

Donors from places such as Canton, Sharon and Stoughton — towns served by the Norfolk County DA's office but not among the towns in the 10th District — dominate Keating's disclosure filed with the Federal Election Commission.

"It takes a lot of money to run for Congress," said Jane Lane, a spokeswoman for Keating. "The first thing any candidate would do is turn to his core supporters, those who have supported him in the past, and encouraged him to run."

By contrast, Jeffrey Perry, a Sandwich Republican, has raised 82 cents of every $1 in donations from the 41 cities and towns in the 10th Congressional District, according to federal records.

"Over 2,000 people have written a check from inside the district," said Perry, who included in that number checks under $200 that aren't part of federal records. "At some level that translates to votes."

As expected, the Cape and Islands represent the bulk of money raised by Perry and Democrat Robert O'Leary.

Though candidates Joseph Malone and O'Leary have also raised slightly more than 50 percent of their itemized donations from outside the district, they are not concentrated in one area as are Keating's.

Malone is a Scituate Republican and former state treasurer and O'Leary is a Democratic state senator from Barnstable.

There is nothing illegal about Keating's contributions, but O'Leary said the fundraising disparity — Keating has raised $300,000 more than he has — should not be construed as voter support in the 10th.

"It gave him an advantage in fundraising early on," O'Leary said. "I believe that advantage goes away for the balance of this campaign."

O'Leary raised just under $200,000 from May to July, including an $11,000 loan from his state funds.

Both Perry and O'Leary have modest state campaign funds — $24,000 and $15,000 respectively — that wouldn't be worth trying to convert to their federal campaigns.

In January, Perry held a fundraiser for his state representative campaign called "Jokes with Jeff." Because he was contemplating a run for the U.S. House seat at the time, he refused to accept any money that night, he said.

"I knew the money couldn't be used in a federal campaign," he said.

Malone said he knows of no precedent for Keating's fundraising maneuver. "I thought it was a bit slick," he said.

Though Keating has moved into an apartment in Quincy to run for the seat, the level of donations from outside the district will likely add to the perception of Keating as a carpetbagger, his opponents said.

"I'm very deeply rooted in this district. I've lived here most of my life, all my adult life," said O'Leary. "(Keating) and I have different biographies coming into this race."

Malone said Keating comes across as a political opportunist, jumping into the race after Attorney General Martha Coakley lost to Scott Brown for U.S. Senate in January's special election.

"I think when you add up a lot of the pieces, the state funds and turning them into federal funds, and see him moving to Quincy and for him to quickly shift from running for attorney general to run for Congress, this is an ambitious guy looking for his next seat," Malone said.

Records indicate Keating and Malone have received a little more than a dozen donations above the $200 threshold from the Cape and Islands.

Lane, Keating's spokeswoman, said the candidate's smaller donations — the ones under $200 that don't have to be itemized — have come from within the district boundaries.

"We're confident that as (Keating) gets to meet with more voters and talks to them about his plans for job creation and the economy, he will add to the solid support he has on the Cape," Lane said.